; 4-6
(defun block-height (b) (aref b 0))

(defstruct point
	x
	y)

(setf p (make-point :x 0 :y 0))

(point-x p)

(setf (point-y p) 2)

(point-p p)
(typep p 'point)

(defstruct polemic
	(type (progn
					(format t"What kind of polemic was it? ")
					(read)))
	(effect nil))

(defstruct (point (:conc-name p)
									(:print-function print-point))
	(x 0)
	(y 0))

(defun print-point (p stream depth)
	(format stream "#<~A, ~A>" (px p) (py p)))
